Canals, aqueducts, and the like, particularly when combined into systems, are typically used to deliver water to agricultural growers for agricultural purposes, particularly for irrigation. They are the primary water-delivery and water-storage systems in many regions. These agricultural-water canal systems are generally open to the atmosphere along most of their extensive lengths. Because of this great exposure to the atmosphere, these canal systems are extremely susceptible to being, and normally are, inoculated or contaminated with air-borne biologicals such as algae. Further, biological contamination of the water reservoirs or other bodies of water that feed agricultural-water canal systems is not unusual, and in such circumstances there is a substantially continuous or repeated loading or charging of biological contamination to the canals.
These agricultural-water canal systems are, as mentioned above, open to the atmosphere along most of their extensive lengths and, further, they are normally accessible from the land along at least some stretches. The canal systems therefore are routinely additionally polluted with macro-biological materials such as aquatic flora, and biological and biologically-derived debris and waste, which ultimately also increase and/or intensify the biological and biologically-derived contamination. Additionally, agricultural wastes, most notably fertilizers and/or soil amendments from adjacent agricultural lands, are commonly flushed to into the canals from the adjacent filter stations belonging to the agricultural grower.
With urban areas expanding into rural areas, water storage areas such as the canal systems are also being polluted by urban wastes, including without limitation fertilizers, organic products, and municipal wastes that are treated and diluted, and then released into agricultural-water canal systems. These nutrient sources contribute to the proliferation of biological build-up in the canal systems. Further, such urban-waste material can itself constitute canal-fouling organic debris if incompletely and/or insufficiently treated and diluted before release.
The microbiological contaminants (“microbials”) from these and possibly other sources propagate and flourish in the typical agricultural-water canal environment. In contrast, the water from an incoming water-delivery system, such as a canal, that is targeted for human uses in urban areas is typically treated by the municipality at a regional water treatment plant, and the water is then sanitarily piped to the consumer. For agriculture uses, however, the water-delivery systems (which routinely are canal systems) extend across vast areas of land as above-ground systems which are open to the atmosphere and accessible from the land, and therefore susceptible to biological contamination as described above. The typical canal system for agricultural uses runs to many miles in length, transports water to multiple water-delivery points along its length, and has varied water-flow rates which are sometimes very low or stagnant.
The typical canal system and its management pose unique problems and challenges, and are in turn beset by a number of adverse circumstances, including without limitation the increasing demand for not merely agricultural water but for unadulterated, or less adulterated, agricultural water. The demand for agricultural water increases with population increases because greater populations have higher agricultural crop requirements, and greater agricultural crop output requires higher irrigation water consumption. The agricultural-water canals must be kept free from macro-biological fouling, and aquatic weed growth (to which algae clings) along the canal must be minimized to keep the water of a canal free-flowing. The treatment of the canals to keep them free flowing is usually conducted on behalf of water districts which are formed to manage water distribution to growers in a particular region or district. (The water districts normally manage and distribute water from a state and/or federal aqueduct system, via the canals, to the growers within the district.)
The individual growers want the water supplied via a water-district canal or, in some instances usually associated with the larger growers, via private canals, to be sufficiently uncontaminated so that it does not plug or foul their intake screens along the canal which are upstream of their pumps or other filters.
Another canal-system problem which is created or aggravated by biological-debris contamination is the plugging of the canal system itself. The flow of water in a canal system is normally gravity driven, that is, the water flows forward in the canal system because it is moving from one elevation to a slightly lower elevation. This gravity-driven water flow is not particularly dynamic, and it normally is not sufficiently fast or forceful to demolish blockages, obstructions and the like in the canal system, or even to prevent a blockage-creating build-up of organic debris. When a section of a canal system becomes plugged with organic debris, the effect is analogous to a log jam (although the plugging material is organic debris such as algae). Such plugging typically, but not always, occurs where the canals run through underground culverts or pipes below road crossings. The water, or at least a large amount of the water, does not flow past the plugged section, and the continued forward flow of water creates a back-up of water upstream of the plugged section. The backed-up water generally will then overflow the banks of the canal system, which typically damages the canal system itself and/or surrounding environs, such as nearby agricultural lands.
Frustrating the pressures for cleaning up canal-system water are governmental regulations concerning canal-system treatment. These regulations are becoming increasingly restrictive and stringent for a number of reasons, including without limitation the ever-increasing proximity of general-population areas to agricultural areas and widening concerns about the water quality of rivers and oceans into which canal systems ultimately discharge their undistributed waters. The use of two types of canal-system water treatment chemicals have been under ever-increasing regulatory pressures. These chemicals are chlorine gas and a commercial product sold under the Magnacide® trademark. (Magnacide® is a federally-registered trademark for bactericides, biocides and herbicides of Baker Hughes Incorporated of Houston, Tex., as assignee of Magna Corporation of Santa Fe Springs, Calif.) The use of chlorine gas presents a risk of a deadly gas release into the atmosphere. The commercial Magnacide® treatment chemicals, and in particular the commercial Magnacide® b microbiocide (U.S. EPA Product Registration No. 010707-10) contains, as its active ingredient, acrolein, at a level of 95 percent by mass. The commercial Magnacide® b microbiocide has a U.S. EPA Restricted Use status (use only by, or under direct supervision of, a certified pesticide applicator) and a toxicity code of 1, which corresponds to a toxicity category of Danger. The commercial Magnacide® h aquatic herbicide (U.S. EPA Product Registration No. 010707-0) has the same 95% acrolein content and the same Restricted Use and toxicity code 1 ratings as Magnacide® b microbiocide.
Acrolein, which is also known as acrylaldehyde, acrylic aldehyde and allyl aldehyde, is an extremely toxic poison and all human exposures thereto, including exposure by inhalation, skin contact, eye contact and ingestion, require medical attention. Acrolein has a high water solubility of 238,000 mg/L, an adsorption coefficient (ability to bind to soil) (Koc) of 0.76, a hydrolysis half-life of 2.04 days, an aerobic soil half-life of 0.16 days, and an anaerobic soil half-life of 6.22 days. Acrolein is listed as a potential groundwater contaminant by the state of California because of its potential to move into ground water based on its water solubility, ability to bind to soil and half-life, all of which characteristics are described above. Acrolein is a toxic air contaminant and as a pesticide is deemed toxic to fish and wildlife. As to specifically its aquatic ecotoxicity, mortality is one of its toxic effects on amphibians, annelids, aquatic plants, crustaceans, fish, insects, mollusks, nematodes, flatworms and zooplankton. As to its average acute toxicity, acrolein is very highly toxic to amphibians, highly toxic to fish, mollusks and zooplankton, and moderately toxic to crustaceans and insects. Acrolein is highly reactive chemically. It can violently react if brought into contact with alkalis or acids and it cannot be used or stored near fire, sparks or heated surfaces.
Copper sulfate and chelated copper products have also become disfavored for aquatic pesticide use due to their high cost and the potential for heavy metal build-up in the agricultural soils receiving irrigation water from canal systems which have been so treated.
Because of the tightening of governmental regulations, and because of the toxicity issues underlying these regulations, the algae and other organic debris problems in many canal systems now are often only being managed by mechanical harvesting, that is, the physical or mechanical removal of these contaminants. This method is costly because it is labor intensive, and it is an inferior approach to canal-system management because only large patches or growth areas of contamination are removed. Reseeding, regrowth and post-removal contamination proliferation are common because complete physical removal, particularly complete physical removal of microbials, is not possible.
For these reasons, there is a serious and long-felt need for an effective, economical, and environmentally sound treatment for, and method to treat and/or remediate, canal systems to eliminate the organic-debris contamination and build-up thereof in canal systems.